Robert Hooke Father of Microscopy 2

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During that historic period known as the Renaissance, after the "dark" Middle Ages, there occurred the inventions of printing, gunpowder and the mariner's compass, followed by the discovery of America. Equally remarkable was the invention of the light microscope: an instrument that enables the human eye, by means of a lens or combinations of lenses, to observe enlarged images of tiny objects. It made visible the fascinating details of worlds within worlds.

Invention of Glass Lenses
Long before, in the hazy unrecorded past, someone picked up a piece of transparent crystal thicker in the middle than at the edges, looked through it, and discovered that it made things look larger. Someone also found that such a crystal would focus the sun's rays and set fire to a piece of parchment or cloth. Magnifiers and "burning glasses" or "magnifying glasses" are mentioned in the writings of Seneca and Pliny the Elder, Roman philosophers during the first century A. D., but apparently they were not used much until the invention of spectacles, toward the end of the 13th century. They were named lenses because they are shaped like the seeds of a lentil.

The earliest simple microscope was merely a tube with a plate for the object at one end and, at the other, a lens which gave a magnification less than ten diameters -- ten times the actual size. These excited general wonder when used to view fleas or tiny creeping things and so were dubbed "flea glasses."

Birth of the Light Microscope
About 1590, two Dutch spectacle makers, Zaccharias Janssen and his son Hans, while experimenting with several lenses in a tube, discovered that nearby objects appeared greatly enlarged. That was the forerunner of the compound microscope and of the telescope. In 1609, Galileo, father of modern physics and astronomy, heard of these early experiments, worked out the principles of lenses, and made a much better instrument with a focusing device.

Anton van Leeuwenhoek (1632-1723)
The father of microscopy, Anton van Leeuwenhoek of Holland, started as an apprentice in a dry goods store where magnifying glasses were used to count the threads in cloth. He taught himself new methods for grinding and polishing tiny lenses of great curvature which gave magnifications up to 270 diameters, the finest known at that time. These led to the building of his microscopes and the biological discoveries for which he is famous. He was the first to see and describe bacteria, yeast plants, the teeming life in a drop of water, and the circulation of blood corpuscles in capillaries. During a long life he used his lenses to make pioneer studies on an extraordinary variety of things, both living and non living, and reported his findings in over a hundred letters to the Royal Society of England and the French Academy.

Robert Hooke
Robert Hooke, the English father of microscopy, re-confirmed Anton van Leeuwenhoek's discoveries of the existence of tiny living organisms in a drop of water. Hooke made a copy of Leeuwenhoek's light microscope and then improved upon his design.

Charles A. Spencer
Later, few major improvements were made until the middle of the 19th century. Then several European countries began to manufacture fine optical equipment but none finer than the marvelous instruments built by the American, Charles A. Spencer, and the industry he founded. Present day instruments, changed but little, give magnifications up to 1250 diameters with ordinary light and up to 5000 with blue light.

Beyond the Light Microscope
A light microscope, even one with perfect lenses and perfect illumination, simply cannot be used to distinguish objects that are smaller than half the wavelength of light. White light has an average wavelength of 0.55 micrometers, half of which is 0.275 micrometers. (One micrometer is a thousandth of a millimeter, and there are about 25,000 micrometers to an inch. Micrometers are also called microns.) Any two lines that are closer together than 0.275 micrometers will be seen as a single line, and any object with a diameter smaller than 0.275 micrometers will be invisible or, at best, show up as a blur. To see tiny particles under a microscope, scientists must bypass light altogether and use a different sort of "illumination," one with a shorter wavelength.

The introduction of the electron microscope in the 1930's filled the bill. Co-invented by Germans, Max Knoll and Ernst Ruska in 1931, Ernst Ruska was awarded half of the Nobel Prize for Physics in 1986 for his invention. (The other half of the Nobel Prize was divided between Heinrich Rohrer and Gerd Binnig for the STM.)

In this kind of microscope, electrons are speeded up in a vacuum until their wavelength is extremely short, only one hundred-thousandth that of white light. Beams of these fast-moving electrons are focused on a cell sample and are absorbed or scattered by the cell's parts so as to form an image on an electron-sensitive photographic plate.

Power of the Electron Microscope
If pushed to the limit, electron microscopes can make it possible to view objects as small as the diameter of an atom. Most electron microscopes used to study biological material can "see" down to about 10 angstroms--an incredible feat, for although this does not make atoms visible, it does allow researchers to distinguish individual molecules of biological importance. In effect, it can magnify objects up to 1 million times. Nevertheless, all electron microscopes suffer from a serious drawback. Since no living specimen can survive under their high vacuum, they cannot show the ever-changing movements that characterize a living cell.

Light Microscope Vs Electron Microscope
Using an instrument the size of his palm, Anton van Leeuwenhoek was able to study the movements of one-celled organisms. Modern descendants of van Leeuwenhoek's light microscope can be over 6 feet tall, but they continue to be indispensable to cell biologists because, unlike electron microscopes, light microscopes enable the user to see living cells in action. The primary challenge for light microscopists since van Leeuwenhoek's time has been to enhance the contrast between pale cells and their paler surroundings so that cell structures and movement can be seen more easily. To do this they have devised ingenious strategies involving video cameras, polarized light, digitizing computers, and other techniques that are yielding vast improvements in contrast, fueling a renaissance in light microscopy.

Robert Hooke Father of Microscopy

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Robert Hooke Father of Microscopy

Date of Birth-Death :(1635-1703)

Country of Birth :UK

Major Discoveries : 

The Cell: first person to coin the word 'cell' to describe the basic unit of life

Defined Hooke's Law: Provided the elastic limit is not exceeded, the deformation of a material is proportional to the force applied to it.

Extinction: two hundred and fifty years before Darwin, he realized the true nature of fossils.
Inventions: invented the wheel barometer, Gregorian telescope and greatly improved the compound microscope.
Jupiter: discovered the red spot of Jupiter and was the first person to report the rotation of this giant planet.
Telegraphy: invented a method of telegraphy based on telescopes and proportional signs in the 17th century!
Underwater: invented a diving bell.
Architecture: played a major role in the re-building of London after the Great Fire of 1665. Designed several buildings, one surviving example is Willen Church in Buckinghamshire.

 Writing by the Scientist :Micrographia(1665)

Inventor, physicist, surveyor, astronomer, biologist, artist…Robert Hooke was all these and more. Some say he was the greatest experimental scientist of the seventeenth century. In the course of his work, he collaborated with renowned men of science like Christian Huygens, Antony van Leeuwenhoek, Robert Boyle, Isaac Newton and the great architect, Christopher Wren.  Hooke's early education began at home, under the guidance of his father, a curate (priest). He entered Westminster School at the age of thirteen, and from there went to Oxford, where he came in contact with some of the best scientists in England. Hooke impressed them with his skill at designing experiments and devising instruments. In 1662, at the age of 28, he was named Curator of Experiments of the newly formed Royal Society of London -- meaning that he was responsible for demonstrating new experiments at the Society's weekly meetings. Hooke accepted the job, even though he knew that the Society had no money to pay him!   Watching living things through the microscope was one of his favorite occupations. He devised a compound microscope for this purpose. One day while observing a cork under a microscope, he saw honeycomb-like structures. They were cells- the smallest units of life. In fact, it was Hooke who coined the term "cell" as the boxlike cells of the cork reminded him of the cells of a monastery.  Perhaps because of his varied interests, Hooke often left experiments unfinished. Others took up where he left off and then claimed sole credit. This sometimes led to quarrels with colleagues. One work that he finished was his book MICROGRAPHIA, a volume that reveals the immense potential of the microscope. It contains fascinating drawings of the things he saw under the microscope. The book also includes, among other things, ideas on gravity, light and combustion that may have helped scientists like Newton while they were developing their own theories on these phenomena. Hooke made valuable contributions to astronomy too. A crater on the moon is named after him in appreciation of his services to this branch of science.

Charles Darwin Gentleman Naturalist

Tags:Charles Darwin Gentleman Naturalist,scientists achievements

Date of Birth-Death : 1809-1882

Country of Birth : UK

Major Discoveries : The theory of natural selection

Writing by the Scientist : Origin of species by means of natural selection(1859)

Born into a wealthy family, Darwin grew up amidst a life of wealth and comfort . His father was a doctor and had similar aspirations for him. It was no surprise therefore that Darwin first studied medicine at Edinburgh. However, it soon became clear to the family, and particularly to young Charles, that he was not cut out for a medical career. He then went to Cambridge to train to become a clergyman . While at Cambridge, Darwin befriended a biology professor John Stevens Henslow, and his interest in zoology and geography grew. An unforeseen opportunity precluded Darwin's plan of becoming a clergyman. He was invited on board the ship, H.M.S. Beagle as a gentleman companion to the captain.
The round-the-world journey on H.M.S.Beagle lasted almost five years. Darwin spent most of these years investigating the geology and life of the lands he visited, especially South America, the Galapagos islands, and Pacific coral reefs. This journey triggered in him, an interest in evolution of life on earth, the diversity in plant and animal life, and how they survived.
Upon his return to England in 1836, Darwin tried to solve the riddles of these observations and the puzzle of how species evolve. He began to develop the theory of evolution that was to make him famous.
Darwin proposed that all life on earth developed gradually over millions of years from a few common ancestors. In other words, the numerous species alive today arose from a single original life form. They developed new characteristics to adjust to different conditions and environments. Those that could not survive perished.
He called this process of evolution - natural selection. All life, he said, is a continuous struggle in which only the fittest can survive. In other words, in the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment.
Darwin was the first of the evolutionary biologists. Until then, people believed that the world they lived in, was the same as what God had created thousands of years ago. Darwin’s theories met with fierce opposition, and even though his theories have been questioned and debated upon, “Darwinism” as his theories are called, remain the first ever documentation on how such a variety of species of plants and animals evolved.
Darwin continued to write and publish his works on biology throughout his life. He lived with his wife and children at their home in the village of Downe, fifteen miles from London. In the later years, Darwin was plagued by fatigue and intestinal sickness. He died on 19 April, 1882, and lies buried in Westminster Abbey.